Effect of Welding Parameters on Defects and Fracture Behavior of Friction Stir Welded 2195-T8 Al-Li Alloy Joints

In this work, the ratio of rotation rate to advancing speed was fixed to 10 to fabricate friction stir welding (FSW) butt joints of 2195 - T8 plates with 7.5 mm in thickness. The results revealed that the heat input of joints along the vertical direction varied with the welding parameters though these parameters had a same ratio. 500-50 and 600-60 joints failed in the thermal affected zone and thermal mechanical affected zone (TAZ/TMAZ), while other joints all failed in stirred zone (SZ). The hardness profile across the joints showed a similar W shape, while the hardness in bottom area increased with the increasing of parameters. Lazy S and kissing - bond defects appeared in all of these joints, and over - burn defect was also found in 1000-100 joint. It is concluded that the heat input distribution gradient during FSW across the joints becomes non-uniform and a sudden change between upper and lower areas even occurs.

Molecular dynamics simulation study on ablation of silicon by water-jet-guided laser

Stillinger–Weber potential and Z-layer energy model were adopted in molecular dynamics simulation to study the ablation of silicon by water-jet-guided femtosecond laser, and comparison was made by ablating silicon with or without water-jet cooling in our simulations. Simulation results indicated that with water-jet cooling, the thermal-affected zone could be reduced in area, and the peak of density could disappear more quickly. It was therefore concluded that water-jet-guided laser could be used to considerably improve the ablation quality of silicon.

The Effect of Fiber Laser Machining Parameters on Thermal-Affected Zone of Carbon Fiber Reinforced Plastic

This study describes the effects of machining parameters on the thermal affected zone (heat-affected zone; HAZ) of carbon fiber reinforced plastic using fiber laser. The HAZ described in this study was defined as the area where only resin was removed. In three experiments, the HAZ area and the removal shape of carbon fiber were investigated. The study revealed that pulsed laser reduces the HAZ more than continuous-wave laser does, but it causes the swelling of the carbon fiber tip. Furthermore, the HAZ decreased as the scan speed increased, even if the number of scans was increased. In addition, it was found that nitrogen could restrain the HAZ and the swelling of carbon fiber.

Finite Element Simulations of Thermal Affected Zone during Bone Drilling

In this study, an elastic-plastic finite element model is used to simulate the thermal affected bone (TAZ) during bone drilling process under the condition of constant applied drilling force. Various drilling times and measurement depths are investigated to explore the size of TAZ and stress distributions within the bone. The results indicate that the maximum TAZ occurs at the interface of cortical bone and cancellous bone. The maximum diameter of TAZ is found to be 3.5 mm in this study.

Finite Element Analysis of Ti-6Al-4V Alloy Crater Geometry for EDM Based on a Single Discharge

Temperature theoretical model of Ti-6Al-4Valloy during electrical discharge machining (EDM) process is established in this paper. Based on finite element thermal analysis, the temperature field of EDM Ti-6Al-4V on a single discharge is simulated with the aid of ANSYS software. The results show that there is a high temperature distribution around the spark point while the thermal-affected zone is quite small. Additionally, the profiles of discharge crater geometry have been predicted and the relation between crater shape and parameters under different current and pulse duration are also explored.

Sensitivity Analysis of Parameters for the Simulation of Thermal Transport in Aquifer: A GSHP System in Chengdu, China

Based on the theory of sensitivity analysis, the local/global sensitivity analysis of parameters for the modeling of thermal transport in aquifer under special groundwater flow and heat source conditions were carried out with the summer running of Groundwater Source Heat Pump (GSHP) system as a study case, by taking the temperature of typical observation points and thermal affected zone (TAZ) of injecting water at the end of summer as the model outputs. The results showed that the sensitivity of each modeling output was various for the different parameter in local analysis. The orders of local sensitivity coefficients of the nine parameters for two modeling outputs were almost coincident. In global sensitivity analysis, the sensitivity of the parameter being investigated was influenced by the different values of other parameters. The two modeling outputs almost had the same variation tendency of global sensitivity with different parameter combinations.